HUB add-on developer Mikey1234 apparently thought it was a great idea to add in-XBMC advertisements to his add-ons (I could rant at why this is not only a horrible idea, but could potentially do a lot of harm to XBMC's reputation with people who don't know any better, but I'll save that for another time). This didn't go down well with HUB, and resulted in Mikey leaving to start his own site called XBMCtalk. Mikey made most of the HUB specific add-ons, so he used that access to update them in order to pop up an ad for his new site and tell people that it is the new home for all their add-ons. Knowing Mikey's history, it probably also installed a new repo without them knowing about it (something he's done before and got him banned from xbmc.org).
HUB's umOuch tried to stop this by using HUB's "Maintenance" add-on to uninstall add-ons and other add-on repositories that Mikey controlled. A lot of users woke up today to find lots of add-ons were mysteriously missing.
Really bad decisions from all parties involved.
Now they're both going at it, various people taking sides, and without doubt some of this will manage to splash on us at XBMC.org. If you thought the occasional mashup or 1channel post was annoying, wait until tons of posts start showing up about "where did all my add-ons go?!".
I really doubt either group wants to "hack" your computer, so the first thing anyone worried should do is take a deep breath and calm down. Both sites are claiming the other is using malware or a virus, but this is just hyperbole.
However, if you happen to use add-ons from one of those sites, please take this time to backup your XBMC data folder, the parent folder that holds the
userdata (wiki) folder. Backing up that parent folder will also back up add-ons as well as all of your settings. You should do this anyways as it's generally good practice for any data that you value.
You also might want to evaluate how much you trust the add-ons installed. Like said before, while we don't want people discussing add-ons that violate our
forum rules (wiki), it's not a personal judgement on those people who wish to use them. When we suggest that you uninstall something, it's normally because it's doing something bad to your XBMC set up, and has nothing to do with personal views on piracy or morals. No matter what your stance on these issues is, I don't think anyone likes the idea of ads in XBMC or an add-on automatically uninstalling other add-ons.